Sunnyside Road in Idaho Falls between I‐15 and Yellowstone Highway is designated as US Highway 26 as well as the Interstate 15 Business Loop which is under the jurisdiction of the Idaho Transportation Department (ITD). The Sunnyside Road corridor in the vicinity of the I‐15 interchange has been under considerable development pressure and rapidly increasing traffic volumes since its construction in 2007. Sunnyside Road was also identified in the Bonneville Metropolitan Planning Organization (BMPO) Transportation System Alternatives Study as one leg of the proposed Inner Beltway FY2019 or later around Idaho Falls. As such, its functional classification will change from principal arterial to strategic arterial.

The planned improvement to extend Old Butte Road southward from its current terminus at Pancheri Drive to Sunnyside Road will construct another leg of the future Inner Beltway. However, the Old Butte Road Extension has been delayed indefinitely.

Public open houses were held September 11 and December 5, 2013, to present preliminary information and alternate roadway configurations that would meet the requirements of the proposed widening of Sunnyside Road. A modification was suggested for Option 2B, moving the recommended signalized access to the center of the existing Sidehill Canal bridge, approximately 175′ west of the 1/16th line. This modified spacing would place the traffic signal 2205′ (0.42 mile) east of the I-15 SB Ramps (measured center-to-center). This change would have an effect on traffic signal coordination and vehicle progression; with a 90-second cycle length, expected progression speeds would drop from 36 mph to 33 mph.